Polymer-encapsulated metal complex catalysts: An emerging and efficient platform for electrochemical CO2 reduction

Over the past decade, electrocatalytic reduction of CO2 has gained substantial attention. However, hardly any of the previous reviews have focused on the systematic discussion of polymer-molecular catalyst composites as an emerging system for the electrochemical transformation of CO2 to value-added products. In this review, we first give a brief overview of the general features of solid-state and molecular catalysts, and then advance the discussion to polymer-catalyst composite systems, with particular emphasis on polymer-encapsulated molecular catalysts, where the coordination environment surrounding molecular catalysts can be modified via polymer encapsulation to promote the overall performance of CO2 electrocatalysis. The elucidation of the possible reaction mechanisms of this emerging electrocatalytic system along with proposed optimization strategies is also summarized and discussed based on recently published reports, followed by the challenges and prospects of their industrial applications at the end of this review. From this review, we hope the audience can gain a comprehensive understanding of the electrocatalytic mechanism of the coordinating polymers and valuable insights into engineering the microenvironment surrounding the metal complexes for potential future research directions.